I’m not 100% sure, but isn’t there a difference in floor height between 3rd row trucks vs. 2 row? On the 3rd row, the floor height is flush with the opening, thus there is nothing to stop anything from rolling out. I think I saw a photo around this site somewhere where I could see that the 2 row trucks have their floors a bit deeper, thus there is a substantial lip to stop stuff from falling out.
Oh, I didn't know that. Could be... I am unhelpful in this conversation it turns out.